JP2011127823A - Heat exchanger and water heater with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tubular heat exchanger with the largest ratio of the capacity to a pipe weight by enabling the sophistication of the heat exchanger while minimizing the increase of the heat exchanger weight and by suppressing the increase of the loss of hydraulic pressure as much as possible. <P>SOLUTION: The heat exchanger includes an outer pipe 105 in which fluid A flows, and two or more inner tubes 103 which are installed in the outer pipe 105 and in which fluid B flows. The outer pipe 105 has a part of spiral-shaped 105b which is exclusively applied to a part where the temperature of fluid A is relatively high and the viscosity is the smallest. Hence, the heat transfer in a flow passage for water is enhanced more effectively, and the increase of the loss of hydraulic pressure is minimized since the area has less viscosity. The tubular heat exchanger with the largest ratio of the capacity to the pipe weight is provided thereby. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat exchanger for exchanging heat between a fluid such as water and two kinds of fluids such as a refrigerant, such as a heat pump type hot water heater, etc., used in equipment such as an air conditioner and a hot water heater. It is.

  Conventionally, this type of heat exchanger is composed of an inner pipe in which a refrigerant flow path is formed and an outer pipe that is provided outside the inner pipe and forms a water flow path between the inner pipe and the inner pipe. A so-called double-tube type for exchanging heat between the refrigerant and water has been devised, and a tube having a spiral shape is used for the outer tube in order to increase the capacity of the heat exchanger (for example, , See Patent Document 1).

  11 and 12 show a conventional heat exchanger described in Patent Document 1, FIG. 11 is a top view of the heat exchanger, and FIG. 12 is a part of the heat exchanger cut out. It is the perspective view which notched the part.

  As shown in FIGS. 11 and 12, the heat exchanger 101 is a double-pipe heat exchanger, and is provided on the outer side of the inner tube 103 and the inner tube 103 having the inside as the refrigerant flow path 102. In this heat exchanger 101, two inner tubes 103 are provided. The water tube 105a has a spiral shape that forms a water flow path 104 between the inner tube 103 and the inner tube 103.

  The inner pipe 103 includes a copper refrigerant pipe 106 and a copper leak detection pipe 107 provided on the outer periphery of the refrigerant pipe 106, and expands the refrigerant pipe 106 or contracts the leak detection pipe 107. As a result, the refrigerant pipe 106 and the leak detection pipe 107 are in close contact with each other. The water pipe 105a is a spiral pipe having a spiral shape and is used over the entire length of the heat exchanger 101.

  The operation of the heat exchanger configured as described above will be described below.

  The heat exchanger 101 is configured such that heat exchange is performed between the carbon dioxide 2 flowing in the refrigerant flow path 102 and the water flowing in the water flow path 104 via the inner pipe 103. And heat transfer is accelerated for the water flow stirring by the water pipe 105a which has a spiral shape, and high performance is achieved. At this time, the water pressure loss (hereinafter referred to as water pressure loss) also increases at the same time.

  Further, in the manufacturing process of the heat exchanger 101, it is necessary to insert the inner pipe 103 into the spiral water pipe 105a. However, the inner diameter of the water pipe 105a is required to be larger by the depth of the spiral groove.

  Therefore, when the water pipe 105a is simply used over the entire length of the heat exchanger 101, the heat exchange capacity of the heat exchanger 101 is improved, but the water pressure loss and weight are also increased.

Japanese Patent No. 4300329

However, in the conventional configuration, the heat exchange capacity increases only by using the spiral water pipe 105a to promote heat transfer in the water flow path 104, but the pipe diameter is increased by the depth of the spiral groove. As a result, the weight of the heat exchanger increases and the material cost increases.

  In addition, the water pressure loss of the heat exchanger also increases, so in order to secure the water transfer flow rate, it is necessary to increase the pump capacity, that is, to increase the pump size, and to accommodate large pumps as the material cost increases. The main body becomes larger.

  Thus, there has been a problem that the material cost cannot be reduced by simply applying the helical tube.

  The present invention solves the above-mentioned conventional problems, and enables the performance of the heat exchanger to be improved while minimizing the increase in the weight of the heat exchanger, and also suppresses the increase in water pressure loss as much as possible. The object of the present invention is to provide a tubular heat exchanger having the largest capacity to weight ratio.

  In order to solve the above-described conventional problems, a heat exchanger according to the present invention includes an outer tube through which fluid A flows, and a plurality of inner tubes that are disposed in the outer tube and through which fluid B flows. A part of the outer tube has a spiral shape, and the spiral shape is limitedly applied to a high temperature portion / high Reynolds number region where heat transfer promotion of the water channel is more effectively exhibited. Thus, the ratio of the capacity to the weight of the heat exchanger (herein referred to as the capacity-weight ratio) can be maximized.

  Moreover, since the viscosity of water becomes small because of the high temperature portion, it is possible to provide a tubular heat exchanger that can suppress an increase in water pressure loss as much as possible.

  According to the present invention, it is possible to improve the performance of the heat exchanger while minimizing the increase in the weight of the heat exchanger, and also suppress the increase in water pressure loss as much as possible, so that the ratio of the capacity to the pipe weight is the largest. A tubular heat exchanger can be provided.

The top view of the heat exchanger in Embodiment 1 of this invention Diagram showing heat exchange capacity of the heat exchanger Figure showing the tube weight of the heat exchanger The figure which shows the heat exchange capacity / weight ratio of the same heat exchanger The figure which showed the water side pressure loss of the heat exchanger Top view of heat exchanger in Embodiment 2 of the present invention Perspective view with part of the heat exchanger cut out Perspective view with part of the heat exchanger cut out AA sectional view of FIG. BB sectional view of FIG. Top view of a conventional heat exchanger Perspective view with part of the heat exchanger cut out

  1st invention is equipped with the outer pipe | tube with which the fluid A flows inside, and the some inner pipe | tube arrange | positioned in the said outer pipe | tube, and the fluid B flows through the inside, and a part of said outer pipe | tube is helical shape Since the spiral shape is limited and applied to the portion where the temperature of the fluid A is relatively high and the viscosity is the smallest, not only the heat transfer promotion of the water flow path is more effectively exhibited, Since the water viscosity is low, the increase in water pressure loss can be minimized, and a tubular heat exchanger having the largest capacity to tube weight ratio can be provided.

  In the second invention, the outer tube is composed of a large-diameter tube having a large tube diameter and a small-diameter tube having a small tube diameter, and the large-diameter tube has a helical shape, and the wall thickness of the large-diameter tube is Due to the effect of the spiral shape even if the wall thickness of the large-diameter pipe is made the same as that of the small-diameter pipe, along with the enhancement of the capacity by the pipe having a spiral shape, which is approximately the same as the wall thickness of the small-diameter pipe Since it is difficult for buckling to occur when bending a tube, it is possible to reduce the weight and provide a tubular heat exchanger with the largest ratio of capacity to tube weight.

  The third invention is characterized in that the minimum inner diameter of the large diameter tube is substantially equal to the minimum inner diameter of the small diameter tube, and the clearance between the spiral tube and the inner tube is the same as the clearance between the small diameter tube and the inner tube. As a result, it is possible to further increase the capacity while maintaining the productivity of inserting the inner tube into the outer tube.

  The fourth invention is characterized in that the outer pipe is provided with an inlet and an outlet for the fluid A and the fluid B, and the flow of the fluid A and the fluid B is opposed to each other. The average temperature difference between the fluid A and the fluid B can be increased to increase the amount of heat exchange, and the performance of the heat exchanger can be improved.

  5th invention sets water A as fluid A and fluid B as carbon dioxide, 6th invention is a hot water supply machine provided with the heat exchanger in any one of the 1st-5th, and a heat exchanger is a heat pump type hot water supply. When used as a heat exchanger for exchanging heat between water and a refrigerant, the carbon dioxide operates in a supercritical state and operates in a higher density than a chlorofluorocarbon refrigerant, High heat pump efficiency can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a top view of the heat exchanger according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing the relationship between the length of the helical tube and the heat exchange capacity of the heat exchanger. FIG. 3 is a diagram showing the relationship between the length and weight of the spiral tube of the heat exchanger. FIG. 4 is a diagram showing the ratio of the heat exchange capacity to the length and weight of the helical tube of the heat exchanger. FIG. 5 is a diagram showing the relationship between the length of the helical tube of the heat exchanger and the water pressure loss.

  In addition, about the same structure as the conventional heat exchanger 101, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In FIG. 1, a heat exchanger 1 is a double-pipe heat exchanger, and an inner tube 103 that forms a refrigerant flow path 102 through which carbon dioxide 2 (fluid B of the present invention) flows, and an inner tube In the case of the heat exchanger 1, the heat exchanger 1 is configured by a copper outer pipe 105 that is provided outside the pipe 103 and in which the water 4 (fluid A of the present invention) flows between the inner pipe 103 and forms the flow path 104 for water. Are provided with two inner tubes 103.

  The inner pipe 103 includes a copper refrigerant pipe 106 and a copper leak detection pipe 107 provided on the outer periphery of the refrigerant pipe 106, and expands the refrigerant pipe 106 or contracts the leak detection pipe 107. As a result, the refrigerant pipe 106 and the leak detection pipe 107 are in close contact with each other.

  The inner tube 103 is spirally twisted with each other, and the center of the spiral is included in the outer tube 105 so as to be substantially coaxial with the axis of the outer tube 105. Accordingly, the water 4 flows between the outer pipe 105 and the inner pipe 103. Moreover, the flow becomes a swirl flow along the spiral of the inner tube 103.

  The outer tube 105 includes a spiral tube 105b having a spiral shape and a smooth tube 105c. The spiral tube 105b is provided only for a length L from the water 4 outlet. Further, at both ends of the outer tube 105 and at both ends of the inner tube 103, inlets 8a and 7a and outlets 8b and 7b are provided, respectively, and an inlet 7a and an outlet 7b of carbon dioxide 2 in the inner tube 103 are provided. And the inflow port 8a and the outflow port 8b of the water 4 of the outer tube 105 are provided so as to face each other.

  In FIG. 2, the horizontal axis is the ratio L (%) of the length of the helical tube 105 b to the length of the outer tube 105, and the vertical axis is the increase rate ΔQ (%) of the heat exchange capability Q of the heat exchanger 1. In FIG. 3, the horizontal axis is the ratio L (%) of the length of the helical tube 105 b to the length of the outer tube 105, and the vertical axis is the increase rate ΔW (%) of the weight W of the heat exchanger 1. In FIG. 4, the horizontal axis is the ratio L (%) of the length of the helical tube 105 b to the length of the outer tube 105, and the vertical axis is the heat exchange capability Q with respect to the increase rate ΔW (%) of the weight W of the heat exchanger 1. Is the ratio ΔQ / ΔW of the increase rate ΔQ (%). In FIG. 5, the horizontal axis represents the ratio L (%) of the length of the helical tube 105 b to the length of the outer tube 105, and the vertical axis represents the increase rate ΔP (%) of the water pressure loss P in the heat exchanger 1.

  The operation of the heat exchanger configured as described above will be described below.

  When carbon dioxide 2 and water 4 flow in from the respective inlets 7 a and 8 a, carbon dioxide 2 using the inside of the inner pipe 103 as a refrigerant of the heat pump flows, and between the inner pipe 103 inside the outer pipe 105. Water 4 flows. These flow directions flow as opposed to each other by the orientation of the inlets 7a and 8a and the outlets 7b and 8b as described above, and the carbon dioxide 2 and the water 4 exchange heat through the wall of the inner tube 103. Accordingly, the temperature of the water 4 increases as it approaches the outlet 8b of the outer tube 105, and the temperature of the carbon dioxide 2 decreases as it approaches the outlet 7b.

  In the present invention, the outer tube 105 is composed of a spiral tube 105b having a spiral shape and a smooth tube 105c, and the spiral tube 105b is provided only for a section of length L from the outlet of the water 4. The heat exchange capability Q of the heat exchanger 1 can be more efficiently increased with respect to the weight increase due to 105b. In the heat exchanger 1, the length L of the helical tube 105b is preferably in the range of 3% to 48% with respect to the length of the outer tube 105.

  As shown in FIG. 2, when the length L of the helical tube 105b is increased, the increase rate ΔQ of the heat exchange capability Q increases, but as the length L of the spiral tube 105b increases, the increase rate ΔQ of the heat exchange capability Q increases. There is a characteristic that becomes smaller. The reason for this is that the higher the temperature of the water 4 is, the lower the viscosity is, so that the Reynolds number is high, and it is easy to be influenced by the turbulent flow acceleration by the spiral tube 105b.

  In order to mass-produce using the spiral tube 105b, it is necessary to insert the inner tube 103 into the spiral tube 105b in the manufacturing process, and the tube diameter of the spiral tube 105b needs to be increased by the depth of the spiral groove. .

  As shown in FIG. 3, the increase rate ΔW (%) of the weight W of the heat exchanger 1 increases in proportion to the length L of the spiral tube 105b. Therefore, the characteristics shown in FIG. 4 are obtained from the characteristics shown in FIGS. 2 and 3. According to FIG. 4, the increase rate ΔQ (%) of the heat exchange capacity Q with respect to the weight increase rate ΔW (%) of the heat exchanger 1 is The spiral tube 105b has a peak in a region where a part of the spiral tube 105b is introduced to the outlet side of the water 4.

According to this, when the spiral tube 105b is in the range of 3% to 48% with respect to the length of the outer tube 105, ΔQ / ΔW is 35% or more, and the spiral tube 105b can be efficiently charged.
That is, if the spiral tube 105b is partially applied in the vicinity of the outlet portion 8b of the water 4, the increase rate ΔQ of the heat exchange capacity Q can be increased, and the weight increases even if the spiral tube 105b is applied to the vicinity of the outlet portion 8b of the water 4. However, the increase in heat exchange capacity is small.

  Thus, rather than simply using the spiral tube 105b over the entire length of the outer tube 105, the ratio of the capacity to the tube weight is the most when the spiral tube 105b is partially applied from the outlet portion 8b of the water 4 by the length L. Can provide a large tubular heat exchanger.

  In addition, if the water pressure loss ΔP generated in the water flow path 104 is simply used over the entire length of the outer pipe 105, the water pressure loss ΔP increases greatly, so that the water conveyance power is excessively required and a pump with a large capacity is additionally required. Become.

  As shown in FIG. 5, it can be seen that the rate of increase ΔP of the water pressure loss P is smaller when the spiral tube 105 b is partially applied to a region near the outlet 8 b of the water 4. This is because the viscosity of the water 4 becomes lower in the region where the temperature of the water 4 is higher, so the water flow path resistance becomes smaller.

  Therefore, when the spiral tube 105b is partially applied in the vicinity of the outlet portion 8b of the water 4, the increase in the water pressure loss ΔP can be suppressed to a smaller value, and the water pressure loss ΔP can be suppressed below the allowable resistance value ΔP1 of the pump. is there.

  As described above, the helical tube 105b is partially limited and applied to the so-called high-temperature portion where the temperature of the water 4 is relatively high and the viscosity is low, so that the helical tube is thrown into the high Reynolds number region. It is possible not only to promote the heat transfer of the water flow path 104 more effectively, but also to suppress the increase in the water pressure loss ΔP because the viscosity of the water 4 is small, A tubular heat exchanger in which the ratio of the heat exchange capacity Q to the weight W of the heat exchanger 1 is the largest can be provided.

  Thus, the heat exchanger 1 according to the first embodiment can effectively perform the heat exchange action between the carbon dioxide 4 flowing in the inner pipe 5 and the water 2 flowing in the outer pipe 3, thereby Heat exchange performance can be improved without extending the tube length of the exchanger 1.

  Moreover, by making the water 4 and the carbon dioxide 2 into the opposite flow, the temperature difference between the water 4 and the carbon dioxide 2 can be increased to increase the amount of heat exchange, and the capacity of the heat exchanger 1 can be further enhanced. Can do.

  In the first embodiment of the present invention, the number of the inner pipes 3 arranged in the outer pipe 5 is two. However, the number of the inner pipes 3 may be more than that and the same effect can be expected. .

  In the first embodiment, the spiral tube 105b is a spiral tube, but the same effect can be expected with a corrugated tube or an internally grooved tube.

  Furthermore, in Embodiment 1 of the present invention, the outer tube 5 and the inner tube 3 are made of copper, but at least one of them may be made of brass, stainless steel, iron having corrosion resistance, aluminum alloy, or the like as a material. Similar effects can be expected.

  Further, in Embodiment 1 of the present invention, the refrigerant flowing through the inner pipe 3 is carbon dioxide 2. However, it is also possible to use a hydrocarbon-based refrigerant, an HFC-based refrigerant (R410A, etc.), or an alternative refrigerant thereof. The effect can be expected.

(Embodiment 2)
FIG. 6 is a top view of the heat exchanger according to Embodiment 2 of the present invention. 7 and 8 are perspective views in which a part of the heat exchanger is cut out and a part thereof is cut out. 8 is a cross-sectional view taken along line AA in FIG. 9 is a cross-sectional view taken along line BB in FIG.

  In addition, about the same structure as Embodiment 1, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In FIG. 6, the outer tube 105 is composed of a small-diameter tube having a small tube diameter and a large-diameter tube having a large tube diameter for improving the scale durability reliability, and the helical tube 105b is replaced by a large-diameter tube and a smooth tube 105c. Is applied to a small-diameter pipe. The wall thickness t1 of the spiral tube 105b that is a large diameter tube is substantially the same as the wall thickness t2 of the smooth tube 105c that is a small diameter tube.

  Further, the clearance t1 between the spiral tube 105b and the inner tube 103 is substantially equal to the clearance t2 between the smooth tube 105c and the inner tube 103, whereby the minimum inner diameters of the large diameter tube and the small diameter tube can be made equal.

  The operation of the heat exchanger configured as described above will be described below.

  Along with higher performance by the spiral tube 105b, the thickness t1 of the spiral tube 105b, which is a large-diameter tube, can be made thinner because the effect of the spiral shape is less likely to cause buckling when bending the tube, and thus the weight can be reduced. Preferably, the thicknesses t1 and t2 of the spiral tube 105b and the smooth tube 105c are the same.

  Further, since the clearance S1 between the spiral tube 105b and the inner tube 103 is the same as the clearance S2 between the smooth tube 105c and the inner tube 103, a higher performance can be achieved while maintaining the productivity of inserting the inner tube 103 into the outer tube 105. Can be achieved.

  As described above, by making the thickness t1 and clearance S1 of the spiral tube 105b substantially the same as the smooth tube 105c, it is possible to improve the performance of the heat exchanger 1 while minimizing the increase in the weight of the heat exchanger 1. In addition, it is possible to provide a tubular heat exchanger that can suppress an increase in water pressure loss as much as possible.

  As described above, the heat exchanger according to the present invention can improve the heat exchange performance of the heat exchanger without increasing the heat transfer area of the inner tube by increasing the tube length. Supercritical heat pump water heater used, supercritical heat pump device for heating brine for heating, air conditioner for home use and business use, washing dryer with drying function by heat pump, grain storage warehouse, etc. In addition to the heat pump device, it can be applied to heat exchange applications such as fuel cells.

1 Heat exchanger 2 Carbon dioxide (fluid B)
4 Water (fluid A)
7a Carbon dioxide 2 inlet 7b Carbon dioxide 2 outlet 8a Water 4 inlet 8b Water 4 outlet 103 Inner tube 105 Outer tube 105b Spiral tube L Length of spiral tube 105b t1, t2 Tube thickness S1, S2 clearance

Claims (6)

A heat exchange comprising: an outer pipe through which fluid A flows; and a plurality of inner pipes arranged in the outer pipe and through which fluid B flows, wherein a part of the outer pipe has a spiral shape. vessel. The outer tube is composed of a large-diameter tube having a large tube diameter and a small-diameter tube having a small tube diameter. The large-diameter tube has a spiral shape, and the wall thickness of the large-diameter tube is the tube thickness of the small-diameter tube. The heat exchanger according to claim 1, wherein the heat exchanger is substantially equivalent to the heat exchanger. The heat exchanger according to claim 1 or 2, wherein the minimum inner diameter of the large-diameter tube is substantially equal to the minimum inner diameter of the small-diameter tube. The inlet and outlet of the fluid A and the fluid B are provided in the outer pipe, and the flow of the fluid A and the fluid B is configured to be opposed to each other. The heat exchanger according to item. The heat exchanger according to any one of claims 1 to 4, wherein the fluid A is water and the fluid B is carbon dioxide. A water heater provided with the heat exchanger according to any one of claims 1 to 5.